The present invention relates to apparatus for warming beverages stored in a bottle, and more particularly to a warmer for use with nursing bottles of the type utilizing disposable inner liners.
FIG. 1 is an exploded perspective view showing a disposable baby bottle assembly 100 of a type including a bottle sleeve (holder) 110 and a disposable inner liner 120 that fits inside of sleeve 110, and is held in place by a cap 130. Sleeve 110 is a substantially cylindrical, hollow structure that is typically molded from a relatively stiff plastic. Sleeve 110 includes a substantially cylindrical outer wall 111 having a ring-shaped lower edge 113 defining a lower opening 114, and a threaded upper edge 115 defining an upper opening 116. Outer wall also defines an optional longitudinal slot 117 for receiving a slidable support member (not shown) therein. Liner 120 typically includes a pliable (e.g., plastic) bag or sac for storing a beverage (e.g., milk or baby formula), and in some instances is preformed to facilitate insertion into sleeve 110. Liner 120 includes an open edge 122 and a bag-like body 125 that is typically inserted through upper opening 116 of sleeve 110 until open edge 122 rests on upper edge 115 of sleeve 110. Cap 130 is a substantially ring-shaped structure that is molded from relatively stiff plastic, and includes threads (not shown) that mate with upper edge 115 of sleeve 110. A rubber or plastic nipple 140 is typically mounted onto cap 130. When assembled, a lip of cap 130 pinches open edge 122 of liner 120 and a lower edge (not shown) of nipple 140 against upper edge 115 of sleeve 110, thereby forming a substantially enclosed beverage chamber defined by liner 120 and nipple 140. Subsequently, as beverage is sucked out of liner 120 through an opening formed in nipple 140, liner 120 collapses inside of sleeve 110. After use, liner 120 is typically discarded, and sleeve 110, cap 130, and nipple 140 are typically washed and reused. Disposable nursers similar to disposable baby bottle assembly 100 are sold by Playtex Products Inc. of Westport, Conn., USA.
The milk and baby formula typically dispensed using disposable baby bottle assembly 100 are preferably consumed warm (i.e., above average room temperature). The heating method recommended by disposable baby bottle manufacturers is to hold the assembly 100 under hot tap water, or to place assembly 100 into a pan of warm water removed from heat source. Alternatively, these manufacturers recommend heating the beverage outside of liner 120, and then pouring into liner 120 after cooling to a safe temperature. Liner manufacturers typically warn against using a direct heat source to heat a beverage stored in a liner due to the danger of overheating the beverage and bursting the liner.
While performing the recommended heating methods (e.g., hot tap water or warm water bath) is relatively convenient at home, such methods are typically not available when traveling. Moreover, heating the beverages outside of the liners is typically difficult when traveling, and may present a dangerous health risk by exposing the beverages to, contaminants while pouring the beverage into the liner. Consequently, beverages are often consumed from disposable baby bottles at an undesirable (e.g., room) temperature.
What is needed is an apparatus that quickly and safely warms beverages stored in disposable baby bottles to a desirable temperature.
The present invention is directed to a bottle warmer for warming a beverage (e.g., baby formula or milk) stored in a disposable baby bottle assembly. The bottle warmer includes a housing having an opening for receiving the bottom edge of the baby bottle, a heat transfer element located inside of the opening that contacts the liner when the baby bottle sleeve is fully inserted into the housing, and a heat generator coupled to the heat transfer element such that heat is transferred to the liner at a preset rate and temperature, thereby safely and reliably heating the stored beverage without danger of overheating the beverage and/or bursting the liner wall.
In accordance with an embodiment of the present invention, the heat transfer element of the bottle warmer includes a cup-shaped container having a closed bottom wall, and a cylindrical outer wall that extends upward from the bottom wall and has a circular upper edge that defines an upper opening. The cup-shaped container is formed from a thermally conductive material such as stainless steel, aluminum or other metal, and may be coated with a non-stick material. The cup-shaped container is mounted in the bottle warmer housing over the heat generator such that, when the bottle assembly is mounted onto the bottle warmer, the upper edge of the heat transfer element slides between the sleeve wall and the liner, and the liner is inserted inside the cup-shaped container. When fully inserted, the liner rests against the bottom wall of the heat transfer element, and portions of the liner contact the cylindrical wall of the heat transfer element. By interposing the cylindrical wall of the heat transfer element between the sleeve and the liner in this manner, heat is efficiently transferred from the heat transfer element to the beverage without having to pass through the sleeve wall. Further, this arrangement maximizes surface contact between the cup-shaped heat transfer element and the beverage-filled liner inserted therein, thereby facilitating the even distribution of heat to the liner to reduce heating time and the danger of local xe2x80x9chot spotsxe2x80x9d.
In accordance with another embodiment of the present invention, a plastic or ceramic insert is mounted in the bottle warmer housing that supports the heat transfer element over the heat generator. The insert includes a donut-shaped bottom wall having a mounting structure formed thereon for holding the bottom wall of the heat transfer element, and a cylindrical outer wall that extends upward from the bottom wall and has a circular upper edge that defines an upper opening. A cylindrical groove is formed between the cylindrical wall of the heat transfer element, which has a relatively small diameter, and the cylindrical wall of the insert, which has a relatively large diameter.
In accordance with yet another embodiment of the present invention, a system is provided that includes a baby bottle warmer and a disposable baby bottle assembly in which the baby bottle sleeve and/or the bottle warmer are provided with a mechanism that turns the sleeve while the disposable baby bottle assembly is pushed into the bottle warmer, thereby causing the liner to slide on the surface of the heat transfer element to prevent sticking.
In accordance with another aspect of the present invention, the heat generator is a portable heat generating system that is powered by a fuel source mounted in the housing of the bottle warmer. In one embodiment, the heat generating system includes a valve and/or control switch, a heat generator, and a removable fuel source. The heat generator is mounted in the bottle warmer housing and located below the cup-shaped heat transfer element. In one specific embodiment, the heat generating system is a combustible gas burning system including a valve assembly for passing a combustible gas (e.g., butane) from a removable container to a gas-burning mechanism. A second manual switch is provided to initiate gas flow from container to the gas-burning mechanism, and the manual ON/OFF switch is used to facilitate ignition of the gas. The gas-burning mechanism includes a ceramic piece that is heated by the small gas flame, and is connected to the heat transfer element such that the heat transfer element acts as a heat sink for the ceramic piece. In accordance with a second embodiment, an electrical heating system includes a switch for passing an electric current from a removable battery to a resistive heating element.